Carbohydrate (keratan sulfate gal-6) sulfotransferase 1 (CHST1)

Abstract

Keratan sulfate (KS) is composed of the repeating disaccharide unit of Galβ1-4GlcNAc (poly-N-acetyllactosamine) with sulfate groups at 6-position of the Gal and GlcNAc residues. Most of GlcNAc residues and half of Gal residues of corneal KS are sulfated, suggesting that sulfation of the Gal residue occurs after sulfation of the GlcNAc residue and determines the extent of sulfation of KS. Keratan sulfate Gal-6-sulfotransferase (KSGal6ST) catalyzes the transfer of sulfate to position 6 of the Gal residue of KS. Therefore, it has been thought that KSGal6ST is responsible for producing highly sulfated KS. KSGal6ST is also able to sulfate sialyl N-acetyllactosamine oligosaccharides. KSGal6ST may be engaged in the biosynthesis of not only KS but also glycoproteins bearing sulfated sialyl N-acetyllactosamine or sulfated Sialyl-Lewis X oligosaccharides.